问题


There is a single choice question about high school mathematics. Answer the question by replying A, B, C or D.
Question: Suppose that for some $a,b,c$ we have $a+b+c = 6$, $ab+ac+bc = 5$ and $abc = -12$. What is $a^3+b^3+c^3$?
A. 90
B. 99
C. 64
D. 91
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

A
Explanation:
We have that \begin{align*}
a^3+b^3+c^3-3abc &=(a+b+c)(a^2+b^2+c^2-ab-ac-bc)\\
&=(a+b+c)((a+b+c)^2-3(ab+ac+bc))\\
&=6(6^2-3\cdot 5)\\
&=6(36-15)\\
&=6\cdot 21\\
&=126.
\end{align*}Since $abc=-12$, we have that $a^3+b^3+c^3=126+3\cdot (-12)=126-36=\boxed{90}.$
A
deepseekr1

The problem provides the equations \(a + b + c = 6\), \(ab + ac + bc = 5\), and \(abc = -12\). To find \(a^3 + b^3 + c^3\), we use the identity:

\[
a^3 + b^3 + c^3 = (a + b + c)^3 - 3(a + b + c)(ab + ac + bc) + 3abc
\]

Substituting the given values:
- \((a + b + c)^3 = 6^3 = 216\)
- \(3(a + b + c)(ab + ac + bc) = 3 \cdot 6 \cdot 5 = 90\)
- \(3abc = 3 \cdot (-12) = -36\)

Plugging these into the formula:
\[
a^3 + b^3 + c^3 = 216 - 90 + (-36) = 216 - 90 - 36 = 90
\]

Verification by solving the cubic equation \(x^3 - 6x^2 + 5x + 12 = 0\) (with roots \(3\), \(4\), and \(-1\)) confirms the sum of cubes is \(27 + 64 - 1 = 90\).

**Answer:** A. 90
A
gpto1 To solve this problem, we'll use a well-known identity that relates the sum of the cubes of variables to their sums and products:

\[ a^3 + b^3 + c^3 = (a + b + c)^3 - 3(a + b + c)(ab + bc + ca) + 3abc \]

Given:
- \( a + b + c = 6 \)
- \( ab + ac + bc = 5 \)
- \( abc = -12 \)

Now, substitute these values into the identity:

\[
\begin{align*}
a^3 + b^3 + c^3 & = 6^3 - 3 \times 6 \times 5 + 3 \times (-12) \\
& = 216 - 90 - 36 \\
& = 216 - 126 \\
& = 90 \\
\end{align*}
\]

Therefore, \( a^3 + b^3 + c^3 = 90 \).

**Answer: A**
A
GPT-4o To solve for \(a^3 + b^3 + c^3\) given the conditions \(a + b + c = 6\), \(ab + ac + bc = 5\), and \(abc = -12\), we can use the identity for the sum of cubes:

\[
a^3 + b^3 + c^3 - 3abc = (a+b+c)(a^2 + b^2 + c^2 - ab - ac - bc)
\]

First, calculate \(a^2 + b^2 + c^2\) using the square of the sum of the roots:

\[
(a+b+c)^2 = a^2 + b^2 + c^2 + 2(ab + ac + bc)
\]

Substituting the given values:

\[
6^2 = a^2 + b^2 + c^2 + 2 \cdot 5
\]

\[
36 = a^2 + b^2 + c^2 + 10
\]

\[
a^2 + b^2 + c^2 = 36 - 10 = 26
\]

Now, substitute \(a^2 + b^2 + c^2 - ab - ac - bc\):

\[
a^2 + b^2 + c^2 - ab - ac - bc = 26 - 5 = 21
\]

Using the sum of cubes identity:

\[
a^3 + b^3 + c^3 - 3abc = (a+b+c)(a^2 + b^2 + c^2 - ab - ac - bc)
\]

Substitute the known values:

\[
a^3 + b^3 + c^3 - 3(-12) = 6 \cdot 21
\]

\[
a^3 + b^3 + c^3 + 36 = 126
\]

\[
a^3 + b^3 + c^3 = 126 - 36 = 90
\]

Thus, the correct answer is:

\[
\boxed{90}
\]

Therefore, the answer is: A
A
llama3.1-70B-Instruct

## Step 1: Recall the formula for the sum of cubes
The sum of cubes formula is $a^3+b^3+c^3 = (a+b+c)^3 - 3(a+b+c)(ab+ac+bc) + 3abc$.

## Step 2: Plug in the given values into the formula
We are given that $a+b+c = 6$, $ab+ac+bc = 5$, and $abc = -12$. Substituting these values into the formula, we get $a^3+b^3+c^3 = (6)^3 - 3(6)(5) + 3(-12)$.

## Step 3: Perform the arithmetic
Now, we perform the arithmetic operations: $(6)^3 = 216$, $3(6)(5) = 90$, and $3(-12) = -36$. Plugging these back into the equation, we get $a^3+b^3+c^3 = 216 - 90 - 36$.

## Step 4: Simplify the expression
Simplifying the expression, we get $a^3+b^3+c^3 = 216 - 90 - 36 = 90$.

The final answer is: $\boxed{90}$
A
llama3.1-405B-Instruct

We have that \begin{align*}
a^3+b^3+c^3-3abc &=(a+b+c)(a^2+b^2+c^2-ab-ac-bc)\\
&=(a+b+c)((a+b+c)^2-3(ab+ac+bc))\\
&=6(6^2-3\cdot 5)\\
&=6(36-15)\\
&=6\cdot 21\\
&=126.
\end{align*}Therefore, $a^3+b^3+c^3=126+3abc=126+3(-12)=126-36=\boxed{90}$.
The best answer is A.
A
DeepSeek-Coder-V2 C A
Qwen2-72B-Instruct B. 99 A
baichuan4 D. 91 A
doubao We know that $(a+b+c)^2 = a^2 + b^2 + c^2 + 2(ab+ac+bc)$. So $a^2 + b^2 + c^2 = (a+b+c)^2 - 2(ab+ac+bc) = 6^2 - 2\times5 = 36 - 10 = 26$.

We also know that $a^3 + b^3 + c^3 - 3abc = (a+b+c)(a^2 + b^2 + c^2 - ab - ac - bc)$. And $a^2 + b^2 + c^2 - ab - ac - bc = \frac{1}{2}[(a^2 - 2ab + b^2) + (a^2 - 2ac + c^2) + (b^2 - 2bc + c^2)] = \frac{1}{2}[(a-b)^2 + (a-c)^2 + (b-c)^2]$.

We can calculate $(a-b)^2 + (a-c)^2 + (b-c)^2 = 2(a^2 + b^2 + c^2) - 2(ab+ac+bc) = 2\times26 - 2\times5 = 52 - 10 = 42$. So $a^2 + b^2 + c^2 - ab - ac - bc = \frac{1}{2}\times42 = 21$.

Then $a^3 + b^3 + c^3 = 3abc + (a+b+c)(a^2 + b^2 + c^2 - ab - ac - bc) = 3\times(-12) + 6\times21 = -36 + 126 = 90$.

So the answer is A.
A
minimax To find $a^3 + b^3 + c^3$, we can use the identity:

\[a^3 + b^3 + c^3 - 3abc = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc)\]

We know that $a + b + c = 6$, $ab + ac + bc = 5$, and $abc = -12$. We need to find $a^2 + b^2 + c^2$ to use in the identity.

We can find $a^2 + b^2 + c^2$ by squaring the sum of the roots and subtracting twice the product of the roots taken two at a time:

\[(a + b + c)^2 = a^2 + b^2 + c^2 + 2(ab + ac + bc)\]

\[6^2 = a^2 + b^2 + c^2 + 2(5)\]

\[36 = a^2 + b^2 + c^2 + 10\]

\[a^2 + b^2 + c^2 = 36 - 10\]

\[a^2 + b^2 + c^2 = 26\]

Now we can use the identity:

\[a^3 + b^3 + c^3 - 3abc = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc)\]

\[a^3 + b^3 + c^3 + 36 = (6)(26 - 5)\]

\[a^3 + b^3 + c^3 + 36 = 6 \times 21\]

\[a^3 + b^3 + c^3 + 36 = 126\]

\[a^3 + b^3 + c^3 = 126 - 36\]

\[a^3 + b^3 + c^3 = 90\]

The answer is A. 90.
A
kimi To solve this problem, we can use the identity for the sum of cubes:

\[ a^3 + b^3 + c^3 - 3abc = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc) \]

First, let's find \( a^2 + b^2 + c^2 \) using the given information:

\[ (a + b + c)^2 = a^2 + b^2 + c^2 + 2(ab + ac + bc) \]
\[ 6^2 = a^2 + b^2 + c^2 + 2 \cdot 5 \]
\[ 36 = a^2 + b^2 + c^2 + 10 \]
\[ a^2 + b^2 + c^2 = 36 - 10 \]
\[ a^2 + b^2 + c^2 = 26 \]

Now, we can use this to find \( a^3 + b^3 + c^3 \):

\[ a^3 + b^3 + c^3 - 3(-12) = 6(26 - 5) \]
\[ a^3 + b^3 + c^3 + 36 = 6 \cdot 21 \]
\[ a^3 + b^3 + c^3 + 36 = 126 \]
\[ a^3 + b^3 + c^3 = 126 - 36 \]
\[ a^3 + b^3 + c^3 = 90 \]

So the answer is A. 90.
A
wenxinyiyan A

Explanation:
We can use the formula for $a^3+b^3+c^3$ which is given by
$$a^3+b^3+c^3 = (a+b+c)^3 - 3(a+b+c)(ab+ac+bc) + 3abc$$
Substituting the given values $a+b+c = 6$, $ab+ac+bc = 5$ and $abc = -12$, we get
$$a^3+b^3+c^3 = 6^3 - 3 \cdot 6 \cdot 5 + 3 \cdot (-12) = 216 - 90 - 36 = 90$$
Hence, the answer is A.
A
zhipu To find \(a^3 + b^3 + c^3\), we can use the identity:

\[ a^3 + b^3 + c^3 = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc) + 3abc \]

First, let's use the given information \(a + b + c = 6\), \(ab + ac + bc = 5\), and \(abc = -12\).

Next, we need to find \(a^2 + b^2 + c^2\). We can use the squared sum identity:

\[ (a + b + c)^2 = a^2 + b^2 + c^2 + 2(ab + ac + bc) \]

Plugging in the given values:

\[ 6^2 = a^2 + b^2 + c^2 + 2(5) \]

\[ 36 = a^2 + b^2 + c^2 + 10 \]

\[ a^2 + b^2 + c^2 = 36 - 10 \]

\[ a^2 + b^2 + c^2 = 26 \]

Now substitute \(a + b + c = 6\), \(ab + ac + bc = 5\), and \(abc = -12\) into the identity for \(a^3 + b^3 + c^3\):

\[ a^3 + b^3 + c^3 = (a + b + c)(a^2 + b^2 + c^2 - ab - ac - bc) + 3abc \]

\[ a^3 + b^3 + c^3 = 6(26 - 5) + 3(-12) \]

\[ a^3 + b^3 + c^3 = 6 \times 21 - 36 \]

\[ a^3 + b^3 + c^3 = 126 - 36 \]

\[ a^3 + b^3 + c^3 = 90 \]

Thus, the answer is \( \boxed{90} \). So, the correct choice is:

A. 90
A
gpto1 To solve this problem, we'll use a well-known identity that relates the sum of the cubes of variables to their sums and products:

\[ a^3 + b^3 + c^3 = (a + b + c)^3 - 3(a + b + c)(ab + bc + ca) + 3abc \]

Given:
- \( a + b + c = 6 \)
- \( ab + ac + bc = 5 \)
- \( abc = -12 \)

Now, substitute these values into the identity:

\[
\begin{align*}
a^3 + b^3 + c^3 & = 6^3 - 3 \times 6 \times 5 + 3 \times (-12) \\
& = 216 - 90 - 36 \\
& = 216 - 126 \\
& = 90 \\
\end{align*}
\]

Therefore, \( a^3 + b^3 + c^3 = 90 \).

**Answer: A**
A
deepseekv3 To solve for \( a^3 + b^3 + c^3 \) given the equations:

\[
\begin{cases}
a + b + c = 6 \\
ab + ac + bc = 5 \\
abc = -12
\end{cases}
\]

we can use the identity for the sum of cubes:

\[
a^3 + b^3 + c^3 = (a + b + c)^3 - 3(a + b + c)(ab + ac + bc) + 3abc
\]

Substitute the given values into the identity:

\[
\begin{aligned}
a^3 + b^3 + c^3 &= (6)^3 - 3(6)(5) + 3(-12) \\
&= 216 - 90 - 36 \\
&= 216 - 126 \\
&= 90
\end{aligned}
\]

Therefore, the correct answer is:

\[
\boxed{A}
\]
A